Detection of superimposed ice on the glaciers Kongsvegen and midre Lovénbreen, Svalbard, using SAR satellite imagery

Abstract Superimposed ice forms when meltwater refreezes onto a sub-freezing glacier surface. The accumulation zones of many Arctic glaciers include large areas of superimposed ice, which for mass-balance purposes have to be distinguished from the ablation zone consisting of glacier ice. We examine the ability of synthetic aperture radar (SAR) satellite sensors to detect superimposed ice on the glaciers Kongsvegen and midre Lovénbreen on Svalbard. Structural analysis of ice cores as well as surface observations from these glaciers in 1999 and 2000 provide a spatial record of superimposed ice. Winter SAR images show three distinct zones, which correspond closely to areas of glacier ice, superimposed ice and firn. This is seen very clearly on Kongsvegen, but not as clearly on the much smaller midre Lovénbreen. One possible explanation for the contrasting SAR signal may relate to the differing air-bubble content of firn, superimposed ice and glacier ice. Thin layers of winter-formed superimposed ice (510 cm) in some places are not seen on the SAR images, indicating that a certain thickness is needed for detection. The equilibrium-line altitude cannot be detected since the SAR cannot differentiate old superimposed ice, superimposed ice formed currently in the accumulation area in summer and superimposed ice formed currently in the ablation zone in autumn and winter.

[1]  M. Adair,et al.  Analytic Formulation of Spaceborne SAR Image Geocoding and ``Value-Added'' Product Generation Procedures using Digital Elevation Data , 1992 .

[2]  R. Bindschadler,et al.  Interpretation of sar imagery of the greenland ice sheet using coregistered TM imagery , 1992 .

[3]  Bernard Lefauconnier,et al.  Glacier balance trends in the Kongsfjorden area, western Spitsbergen, Svalbard, in relation to the climate , 1999 .

[4]  R. Kwok,et al.  Greenland Ice Sheet Surface Properties and Ice Dynamics from ERS-1 SAR Imagery , 1993, Science.

[5]  E. Isaksson,et al.  Measuring snow and glacier ice properties from satellite , 2001 .

[6]  Tore Guneriussen,et al.  Firn-line detection on Austre Okstindbreen, Norway, with airborne multipolarization SAR , 2001, Journal of Glaciology.

[7]  Henri Laur,et al.  Derivation of the backscattering coefficient s0 in ESA ERS SAR PRI products , 1996 .

[8]  C. Benson,et al.  Field observations and experimental and theoretical studies on the superimposed ice of McCall Glacier, Alaska , 1976 .

[9]  Jon Ove Hagen,et al.  Long-Term Glacier Mass-Balance Investigations in Svalbard, 1950–88 , 1990, Annals of Glaciology.

[10]  Christian Mätzler,et al.  Applications of the interaction of microwaves with the natural snow cover , 1987 .

[11]  R. Armstrong,et al.  The Physics of Glaciers , 1981 .

[12]  Jan-Gunnar Winther,et al.  Landsat TM derived and in situ summer reflectance of glaciers in Svalbard , 1993 .

[13]  R. M. Koerner,et al.  Some Observations on Superimposition of Ice on the Devon Island Ice Cap, N.W.T. Canada , 1970 .

[14]  K. Melvold,et al.  Evolution of a Surge-Type Glacier in its Quiescent Phase: Kongsvegen, Spitsbergen, 1964–95 , 1998, Journal of Glaciology.

[15]  K. C. Partington.  Discrimination of glacier facies using multi-temporal SAR data , 1998 .

[16]  Olav Liestøl,et al.  The glaciers in the Kongsfjorden area, Spitsbergen , 1988 .

[17]  Bernard Lefauconnier,et al.  Mass Balance Methods on Kongsvegen, Svalbard , 1999 .